In a pulse jet filter cleaning system, the dust is collected on the filter media and when the cake of dust is of appropriate thickness and structure to cause undue pressure drop, a pulse or pulses of compressed air hit or shock the filter media and knock the cake off. This pulse may sometimes be accompanied by physical shaking and even reverse air flows, depending on design. When the cake is removed correctly from the filter, the system removes dust from its assigned environment and has a normal filter life. When the cake is not removed efficiently, the filter life can be significantly shortened.
Pulse jet cleaning systems specify the compressed air inlet pressure to the manifold and pulse valves necessary for effective dust removal. The pulse valve sends a given volume of air to the filter at a predetermined velocity to strike and clear the cake. The actual amount of air is dependent upon the pulse nozzle being fed compressed air at a predetermined and fixed pressure. The cleaning system must receive the correct pressure and a steady repeatable pressure level for each pulse, particularly if timers are used to control the pulses.
A typical pulse jet filter cleaning system uses one control valve to pulse two filters at a time. One row of filters typically consists of four filters per module. Each row thus requires two control valves per row.